launch a tennis ball at 40 degrees above horizontal from the top of a platform t
ID: 1551762 • Letter: L
Question
launch a tennis ball at 40 degrees above horizontal from the top of a platform that is 20 meters above the ground. If the initial speed is 15 m/sec, what is the final speed when it strikes the ground? (Use energy conservation) Atwood's machines is shown in the diagram. The masses are attached through a massless and frictionless pulley. They were both hung 6 meters above the ground initially. The M = 5 kg, and the m = 4 kg. Find the speed of the system when the big M touches the ground. In the following diagram M=5 kg, m=2 kg and the kinetic frictional coefficient is 0.300 between the surface and the big M. Find the work down by the friction as the big M slides through a distance of 3 meters. Find the speed of the small m when it hits the ground. A synchronous space probe is orbiting around Mars. The radius of Mars is 3370 km and the mass is 6.42 times 10^23 kg. The self-rotation period is 24.6 hours. Find the orbital speed of the probe. Find the altitude of the probe above the Martian surface.Explanation / Answer
17. on M,
In vertical, N = M g
f = uk N = uk M g = 0.3 x 5 x 9.8 = 14.7 N
Work done = - f .d
= - 14.7 x 3 = - 44.1 J
18. Work done by gravity = m g d = 2 x 9.8 x 3 = 58.8 J
Applying work - ennergy theorem,
Work done by friction + work done by gravity = change in KE
-44.1 + 58.8 = (5 + 2) v^2 /2 - 0
v = 2.05 m/s
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